The invention concerns a coating device for material webs of, for example, paper or cardboard wherein a doctor blade or doctor roll acts on the web in the area of a backing roll carrying the web, or acts directly on the backing roll. An applicator chamber for the coating substance is provided in which the coating substance can be fed to the web or the backing roll, or to the doctor blade or doctor roll through a mouth that extends parallel to the web or the backing roll across the width of the web.
Such a coating device is known from DE-C 35 13 063. In the case of this coater there is provided, at the doctor blade and the backing roll supporting the material web, a relatively large and spacious application space which on the entrance side of the material web is defined by a front wall that features outlet openings. This front wall extends toward the backing wall so as to almost make contact with it. The document says nothing about the purpose of these outlet openings.
The problem underlying the invention is to improve on such or similar coaters (see also German application P 36 12 248), the quality of the applied coating in terms of uniformity. Due to the high web speeds it appears to be difficult with the prior applicator devices of the categorial type to prevent the occurrence of turbulences in the coating substance.